This counts IGMPv3 ALLOW type membership reports, the report type a receiver sends to add one or more additional sources to its already-established include-mode source list for a group, without a full mode change. An admin monitoring fine-grained source-list adjustments on an SSM-enabled service would see this counter increment whenever a client adds a new permitted source incrementally, rather than replacing its whole source list at once. A steady trickle of Allow reports on a stable service would reflect normal, incremental expansion of permitted sources rather than any full renegotiation event.